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Samsung 4K IR receiver botch repair

During the beginnings of stay-at-home season of 2020 a guy nearby was selling a couple of years old 55 inch 4K Samsung 9000 series TV. He set the minimum bid to approximately 80 euros because the TV had issues with powering on with the remote. It had a connect-box thingy and an RF remote. I got it for the winning bid of 100 euros. A 20 minute drive later I had picked it up and was on my way home.

This was the top Samsung 55 inch model in 20142015 and cost a whopping 3000 EUR new. 12 times more than the last TV I bought new, a 40 inch Philips and around 30 times more than I paid for the TV this replaced. BUT it was somewhat defective as the seller mentioned, there was something up with it’s willingness to power on.

The RF remote worked fine, albeit sometimes there’s a very annoying delay before the TV responded. The TV did power on fine some times, but it would stop all of the sudden, seemingly at random. This was curious indeed. The debugging process started, as it often does, with a new remote. I ordered a generic Samsung-compatible remote. In a week or so the remote was delivered by the Postal Fairy, but it exhibited the exact same symptoms.

Some internet searching later I suspected the IR board being fucked. So I carefully laid the giant TV on a blanket and opened it up.

Potato quality photo of the innards.

Look at that gorgeous power supply. Compared to the cheap shit TVs I’ve had before this is truly a very well engineed power supply. The IR sensor is the little bugger in the left corner of the photo. It’s on a separate PCB connected via a small cable. It’s very easy to disconnect, but unfortunately quite hard to source on the internet.

Potato quality photo of the IR pcb.

My initial inspection of the PCB led me to think it was fine and I plugged it in again. The TV worked for a couple of hours but failed to register IR events again.

I took it apart again and took some macro photos of the sensor:

BW close-up of the broken IR sensor.

As you can see the sensor has a huge (well, large compared to the size of the sensor) crack in it. Being only 6 or 7mm wide, it’s quite small and my ageing eyes can almost be forgiven for not seeing the crack. Lucky for me the engineering on these PCBs is top notch and they actually silk-screened what the individual pins are for. I traced the IR data pin and determined that the pinout of the sensor was:

1 GND 
2 VCC 
3 DATA 
4 GND

Since this is an expensive piece of consumer electronics, I assumed they would use a respected brand of IR sensor. Vishay came to mind and they do, in fact, have a part TSOP75238 that looks a lot like the pictured and has the same pinout.

The local electronics store did not have this exact part, but had another part TSOP361, which is a slightly larger Vishay sensor with 4 pins, but they are switched around:

1 GND
2 Not connected
3 VCC
4 DATA

This was nothing to worry about since I can just wire it differently. I took some wires and some hot glue, and I give to you, internet, the botched repair of an IR sensor for a very expensive TV:

The glorious botch repair.

After plugging it in the remote started working again. The new sensor does not fit quite right in the TV chassis so the angles and range of the remote is somewhat limited. I have ordered the appropriate replacement sensor, but for now I can live with having to aim at the TV when turning it on. The sensor has been working for weeks with very few issues, and I am a happy owner of yet another piece of refurbished electronics.

Thanks for reading and stay safe.

/J

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